The present invention generally relates to air-exhaust mixer assemblies, and more specifically, but not exclusively, concerns a compact air-exhaust mixer assembly that minimizes the number of required modifications for installation to preexisting air/exhaust plumbing.
Exhaust gas recirculation (EGR) is used to reduce pollution generated by engines and other combustion devices. With EGR, a portion of the exhaust gas generated by the engine is mixed into the air intake in order to reduce the amount of pollutants expelled into the atmosphere. Typical air-exhaust mixer assemblies, such as venturi type mixers, occupy a large amount of space so as to ensure that the exhaust gas and intake air are completely mixed. Incomplete mixing of the air and exhaust gases can lead to the creation of increased concentrations of pollutants in the exhaust gas. To ensure complete mixing of the gases, venturi type mixers typically have long mixing cavities. Other types of mixers have mixing cavities with large lengths, widths and/or heights in order ensure complete mixing of the gases. These large mixers in turn makes retrofitting of air-exhaust mixers to engines quite expensive, because the plumbing of the engine has to be extensively modified in order to accommodate the large air-exhaust mixers. Another problem is that venturi type mixers significantly reduce the pressure of the mixed gas supplied to the engine. Therefore, there has been a long felt need for a compact air-exhaust mixer that is relatively inexpensive to manufacture and install, and that minimizes gas pressure drop across the mixer.
An air-exhaust mixer assembly includes an air intake to supply air and an exhaust gas intake to supply exhaust gas. A mixer is fluidly coupled to the air intake and the exhaust gas intake. The mixer has an inner passage and an outer passage defined therein along a longitudinal axis. The inner passage and the outer passage are constructed and arranged to deliver the air and the exhaust gas ready for mixing by expanding the air and exhaust gas in radially opposite directions with respect to the longitudinal axis.